This invention relates to pour and/or spray guns for dispensing a plurality of components and more particularly relates to pour or spray guns for mixing and dispensing reactive components of high viscosity, and/or conveying pressures.
The use of high viscose materials, such as polymeric resins has come into greater use due to the problems of run off from conventional urethane adhesives. Since the consistency of these materials is rather dense, it has been necessary to provide some method of mixing them and then applying them through a dispenser to the workpiece. For light viscosity materials or adhesives the dispenser is in the form of a spray gun, also known as a mixing gun. For the heavier materials the dispenser may be provided with a rotating mixer much like that disclosed in U.S. Pat. No. 3,795,364. In this device the two highly viscose materials are delivered to a chamber and thoroughly mixed by a motor-driven grid. Among the problems with these devices is the difference in volumetric flow because the materials used are not always of the same viscosity and pressure. Thus, one will have a flow rate slightly slower or faster than the other, creating a lead or lag problem resulting in considerable waste caused by frequent start-stop operation. Other problems occurring relate to the cleaning or flushing out of the gun when it is not in use. Frequently, with prior art guns, it has been found quite difficult to clean or flush them because of their complex construction. The patent referred to above solves some of these problems by providing a mixing head which eliminates all valves to prevent clogging or jamming and the consequent difficulties of cleaning and flushing the device. The latter device, while satisfactory for some purposes, lacks versatility because while two highly viscose materials may be easily mixed, the control of the flow of these materials is provided at the source. Because the source or container in which the materials are stored may sometimes be a great distance from the gun or mixing head, considerable waste can result because of the lead or lag time between the two fluids when the device is operated. Further, since there are no valves present in the device described in the patent referred to above, it does not lend itself readily to frequent stop-start, hand-held use, since operation is begun or stopped by activating or deactivating the pumping means on the storage containers.